In coal burning power plants, fly ash particles are entrained in the waste gas and must be removed prior to discharge of the waste gas into the environment. Common methods for removal of the fly ash include electrostatic precipitators, baghouses, and scrubbers.
One method for disposal of the collected fly ash particles is to slurry the collected particles and transport the slurry by pipeline to a suitable disposal site. This disposal method requires little handling of the fly ash and, therefore, can be relatively inexpensive to perform.
The disposal method, however, can have drawbacks. The slurry can solidify in the pipeline during transportation of the slurry to the waste disposal site, particularly when the slurry pump malfunctions or other flow stoppages occur. The solidified deposits resemble concrete and can partially or totally block the pipeline, thereby interrupting operation of the plant. Such deposits can be very difficult and expensive to remove. Because solidification is more likely to occur in higher calcium fly ashes, power plants using this waste disposal method have had to use more expensive, lower calcium coal to generate power.